Electric hammer



Sept. 2, 1941. M. w. KROLL ELECTRIC HAMMER Filed June 10, 1 940 W im R .5 am m m m a fin w L Q% INNJ. r I, .w\ .QN WW Mn Patented Sept. 2, 1941 ELECTRIC Martin W. Kroll, Radersburg, Mont., assignor of one-half to M. Lloyd Parcells, Columbus, Mont., and twenty-five per cent to Frank K. Le Sage,

Butte, Mont.

Application June 10, 1940, Serial No. 339,792

3 Claims.

This invention relates to an electric hammer and has for an object to provide a device of this character having a solenoid which will not overheat when carrying su'flicient current to create a magnetic field sufliciently strong to cause the plunger or hammer to strike a blow of greater force than conventional devices of this character,

this being accomplished by forming the coil of.

the solenoid of heavy walled copper tubing through which water is circulated.

A further object is to provide an electric hammer which utilizes the impact of the returning hammer or plunger for the purpose of actuating the water-circulating pump to cool the coil and to supply water for wet drilling when desired.

A further object is to provide a device of this character having an external circuit interrupter adapted to maintain the current in the solenoid coil until the hammer or plunger has reached the center of the magnetic field thus permitting constant acceleration from the starting point of the hammer or plunger until it has reached the center of the magnetic field, the mechanical arrangement being such that the hammer strikes the chuck of a drill or other tool just before it has traveled past the center of the magnetic field thus making delicate adjustment of the circuit breaker unnecessary.

A further object is to provide a device of this character which will be flexible due to the comparative ease with which cables to carry current for operation may be moved from one location Figure 3 is a cross sectional view taken on the line 3-3 of Figure 1.

Figure 4 is a side elevation of the hammer showing diagrammatically the water container, source of current and circuit breaker.

Figure 5 is a detail longitudinal sectional view of a portion of the heavy walled insulated copper tubing forming the coil of the solenoid.

Referring now to the drawing in which like characters of reference designate similar parts in the various views, In designates circular heads which are connected by bolts I 2 to form the frame of the hammer. A solenoid is mounted between the heads and comprises a cylinder 83 formed of metal of such characteristic as to offer minimum interference with the magnetic field and yet hard enough to resist abrasion, a metal consisting of sixty percent copper, thirty-nine percent zinc and one percent manganese, being one type of metal suitable for this purpose. The cylinder 53 forms a metallic liner for the bore of a spool M having a tubular body I5 and disk heads is which are perforated to receive the four tie bolts l2. Mounted on the tie bolts between the heads are spacing tubes H. The coil of the solenoid is formed of a plurality of spirally wound convolutions of heavy walled copper tubing l8 which permits the circulation of water through the tubing to prevent over-heating from the intense current density required to create the powerfulmagnetic field necessary to strike the heavy blow with the hammer or plunger I9 which is slidably to another, which will be lower in first cost of manufacture than a pneumatic type of drill due to the simplicity of the device, which will be of extremely high efliciency in that the current consumption while the current is on is only used about one-third of the complete reciprocating cycle or operating time, so that the constant energy consumption will be relatively small.

A further object is to provide a device of this character which will be formed of a few strong, simple and durable parts, which will be inexpensive to manufacture, and which will not easily get out of order.

With the above and other objects in view the invention consists of certain novel details of construction and combinations of parts hereinafter fully described and claimed, it being understood that various modifications may be resorted to within the scope of the appended claims without departing from the spirit or sacrificing any of the advantages of the invention.

In the accompanying drawing forming a part of this specification:

Figure 1 is a longitudinal sectional view of an electric hammer constructed in accordance with the invention.

Figure 2 is a cross sectional view taken onthe line 22 of Figure l. l

mounted in the metallic liner 13.

As best shown in Figure 5, the copper tubing is insulated preferably by spirally winding insulating tape 20 over the copper tubing and coating it with an insulating varnish before winding it on the tubing. Due to the water cooling of the tubing the insulation requirements are minimized because of the absence of excessive heat in the solenoid. If desired, the tubing may be coated interna y with insulating or other material, although is is not essential.

The mme'r; ionplunger I9 is formed of any suitable metal to be influenced by the magnetic field created by the solenoid and is of greater length than the solenoid. The hammer or plunger is equipped at the exposed end with a head 2| which is retracted toward the adjacent head IU of the frame by four helical springs 22. Each spring has one end secured to the head 2| by an eye bolt 23 and has the other end secured to the head ID by an eye screw 24 having an adjusting nut 25 which bears against the outer face of the head I to adjust the tension of the spring.

The free end of the hammer or plunger is disposed in alinement with a cylindrical drill chuck 26 having a disk head 21 disposed to overlap the adjacent head 16 of the solenoid and being disposed in the path of lthe hammer or plunger l8 when drawnthrough the solenoid by the magnetic field thereof at great velocity. The drill chuck is formed of non-magnetic metal and is slidably fitted in a tubular housing 28 formed integral with the adjacent head In of the frame. A helical spring 29 is sleeved on the housing and one end abuts the head Ill of the frame while the other end abuts the disk head 21 of the chuck to return the chuck to normal position after each blow of the hammer or plunger.

A drill steel 30 having an axial bore 3| is secured in the drill chuck. A shock absorbing washer32 is disposed between a disk head 33 integral with the housing 29 and a disk head 34 threadedly engaged with the drill chuck 26. The drill chuck is provided with an axial opening 35 which registers with the bore of the drill steel and which is provided with branches 36 which communicate with a passage 31 in the housing- 28, through which water may be supplied for wet drilling as will hereinafter be described.

The hammer or plunger rebound absorbing apparatus is combined with a water cylinder 38 i which is formed integral with the head ll) of the frame adjacent the exposed end of the ham- .mer or plunger IS. A piston 39 is disposed in the cylinder and is provided with apiston rod 40 which projects from the head 4| of the cylinder and terminates in a disk head 42. A shock absorbing spring 43 is sleeved on the plunger between the head 4| of the cylinder and the head 42' of the plunger and serves to move the piston in a retrograde direction to follow the hammer or plunger IS a short distance and move the piston 39 through its intake stroke. When the plunger or hammer is retracted by the strong springs it impinges against the head 42 of the piston rod and the shock is cushioned by the I shock absorbing spring 43 while at the same time the piston 39 is I moved through its discharge stroke.

An intake connection 44 is secured to the head In of the frame which also forms a head of the water'cylinder 38 and is controlled by a check valve 45. An outlet connection 46 is secured in the head In of the cylinder and is controlled by a check valve 41. These valves operate alternately in the usual manner during operation of the circulating piston 39 to draw water through a pipe 48 from a conventional container 49 into the water cylinder and expel it through a pipe 50 which'is connected to a hollow fitting 5| secured to one end of the innermost convolution of the heavy walled copper tubing I8 of the solenoid core.

A hollow fitting 52 is secured to the end of the outermost convolution of the heavy walled copper tubing of the solenoid core and is connected by a pipe 53 to a hollow fitting 54 which communicates with the passage 31 in the housing 28 above described. Thus water is circulated through the tubing forming the solenoid coil and discharged through the bore 3| of the drill steel 30 to accomplish wet drilling.

Current is supplied to the coil of the solenoid I by conductor wires 55 and 56 secured respectively to the hollow fittings 5| and 52 on the ends of the coil. Any suitable source of current supply may be used, the same being indicated as a generator 51 in the present embodiment of the invention.

The current interrupter comprises a disk 58 formed of insulating material and fixed to a shaft 59 formed of metal with high current carrying capacity and which is connected to one side of the generator by a wire 60. An arcuate contact BI is connected to the shaft by a conductor arm 62 and both are secured im any preferred manner as a unit with the insulating disk 58. A brush 63 is connected to the conductor wire 56 which leads from one end of the solenoid and has wiping engagement with the contact 6 The duration of the current application is governed by the length of the arcuate conductor 6| as well as the speed at which the shaft 59 rotates. and the lattergoverns the number of impulses transmitted to the solenoid cell which in turn governs the number of blows struck by the hammer or plunger l9. One current distributor may be utilized to operate a number of electric hammers simultaneously.

Since the operation of the parts has been described as a description of the parts progressed. it is thought the invention will be fully understood without further explanation.

What is claimed is:

1. An electric hammer comprising, a frame, a solenoid mounted in the frame formed of a plurality of spirally wound insulated convolutions oi. heavy walled copper tubing permitting the circulation of water through the tubing to prevent over heating, a hammer movable through the solenoid under the influence of the magnetic field thereof, means for retracting the hammer. a water pump connected to copper tubing, a piston for. the pump in the path of retrograde movement of the hammer. a spring for moving the piston to follow the hammer during advance movement of the hammer, retrograde movement of the hammer after each actuation moving the piston to circulate water through said tubing.

2. An electric hammer comprising, a frame, a

solenoid mounted in the frame formed of a plurality of spirally wound insulated convolutions of metal tubing, a metal liner in the solenoid, a hammer of magnetic material movable through the liner under the influence of the magnetic field of the solenoid, a tool chuck carried by the frame operated by the hammer, means for retracting the hammer after each actuation, a water pump connected to said tubing, 9. piston for the pump in the path of retrograde movement of the hammer, a spring for moving the piston to follow the hammer during advance movement of the hammer, retrograde movement of the hammer after each actuation moving the piston for circulating water through said tubing.

3. An electric hammer comprising, a frame. a solenoid mounted in the frame formed of a plurality of spirally wound insulated convolutions of heavy walled copper tubing permitting the circulation of water through the tubing to prevent over heating, a hammer movable through the solenoid under the influence of the magnetic field thereof, a tool chuck carried by the frame in the path of movement of the hammer under the influence of the solenoid, springs connected to the frame and to the hammer for withdrawing the hammer to neutral position after each operation, a pump cylinder carried by the frame. a piston in the cylinder in the path of retrograde movement of the hammer, a spring for moving the piston to follow advance movement of the hammer, water inlet and outlet valves in the cylinder, rebound of the hammer after each actuation moving the piston through a discharge stroke, and water connections connected to said valve and to said tubing of the solenoid for circulating water through said tubing.

MARTIN W. KROLL. 

